In the offshore industry, the exploration and production of gas and petroleum is conducted through tubular (casing) of various diameters. The wellbore typically includes casing that extends downwardly for several thousand yards. When the well is abandoned, the owners of the wellbore are required to perform an operation called plugging and abandonment. Federal regulations and guidelines require that the well bore be sealed, entailing the removal of some existing casing to place a plug. Conventionally, the cutter in use can cut and mill the innermost section of casing. However, cutting larger diameter casing still existing lower in the well bore must still be performed by a smaller diameter tool because the operator has to negotiate through the smallest inner diameter (“I.D.”) restriction of casing before the larger casing downhole is reached. In addition, the inner and outer casing may not be concentric, forcing the cutter to have to go through the smaller inner casing and exit through a cut section before cutting and milling the larger casing without being able to center the cutter in the larger casing. This painstaking and costly process can take several days, if it can be done at all without the removal of the restriction.
Devices that hydraulically actuate stabilizers and cutting blades with tubing pressure are disclosed in U.S. Pat. No. 5,265,675 and U.S. Pat. No. 6,679,328. Rack and pinion drive systems for downhole tools are shown in U.S. Pat. Nos. 6,877,564; 6,957,703 and 8,162,066.
As can be seen, there is a need for a device that can cut and mill tubular of various inside diameters in an efficient manner, thereby saving time and expense.